1. Field of the Invention
The present invention relates to coil parts and a method of manufacturing the same, and more particularly, to coil parts and a method of manufacturing the same that are capable of implementing high common-mode impedance in the same frequency, improving performance and capacity, and reducing manufacturing costs and improving productivity through simplification of structure and processes.
2. Description of the Related Art
Electronic products, such as digital TVs, smart phones, and notebook computers, have functions for data communication in radio-frequency bands. Such IT electronic products are expected to be more widely used since they have multifunctional and complex features by connecting not only one device but also USBs and other communication ports.
Here, for higher-speed data communication, data are communicated through more internal signal lines by moving from MHz frequency bands to GHz radio-frequency bands.
When more data are communicated between a main device and a peripheral device over a GHz radio-frequency band, it is difficult to provide smooth data processing due to a signal delay and other noises.
In order to solve the above problem, an EMI prevention part is provided around the connection between an IT device and a peripheral device. However, conventional EMI prevention parts are used only in limited regions such as specific portions and large-area substrates since they are coil-type and stack-type and have large chip part sizes and poor electrical characteristics. Therefore, there is a need for EMI prevention parts that are suitable for slim, miniaturized, complex, and multifunctional features of electronic products.
A common-mode filter of EMI prevention coil parts in accordance with the prior art is described below in detail with reference to FIG. 1.
Referring to FIGS. 1 to 2, a conventional common-mode filter includes a lower magnetic substrate 10, an insulating layer 20 disposed on the lower magnetic substrate 10 and including a first coil pattern 21 and a second coil pattern 22 which are vertically symmetrical to each other, and an upper magnetic body 30 disposed on the insulating layer 20.
Here, the insulating layer 20 including the first coil pattern 21 and the second coil pattern 22 is formed on the lower magnetic substrate 10 through a thin-film process. An example of the thin-film process is disclosed in Japanese Patent Application Laid-Open No. 8-203737.
And, a first input lead pattern 21a and a first output lead pattern 21b for inputting and outputting electricity to and from the first coil pattern 21 are formed on the insulating layer 20. A second input lead pattern 22a and a second output lead pattern 22b for inputting and outputting electricity to and from the second coil pattern 22 are formed on the insulating layer 20.
In more detail, the insulating layer 20 consists of a first coil layer including the first coil pattern 21 and the first input lead pattern 21a, a second coil layer including the second coil pattern 22 and the second input lead pattern 22a, and a third coil layer including the first output lead pattern 21b and the second output lead pattern 22b. 
That is, the first coil layer is formed by coating an insulating material after forming the first coil pattern 21 and the first input lead pattern 21a on an upper surface of the lower magnetic substrate 10 through a thin-film process.
And, the second coil layer is formed by coating an insulating material after forming the second coil pattern 22 corresponding to the first coil pattern 21 and the second input lead pattern 22a on an upper surface of the first coil layer through a thin-film process.
Next, the third coil layer is formed by coating an insulating material after forming the first output lead pattern 21b and the second output lead pattern 22b on an upper surface of the second coil layer through a thin-film process for external output of the first coil pattern 21 and the second coil pattern 22.
At this time, the first coil pattern 21 and the second coil pattern 22 may be electrically connected to the first output lead pattern 21b and the second output lead pattern 22b through via connection structures, respectively.
Meanwhile, the first coil layer to the third coil layer may be formed in a sheet shape and combined in a stack-type to configure the above-described insulating layer including the first and second coil patterns, the first and second input lead patterns, and the first and second output lead patterns.
However, in the conventional common-mode filter configured as above, the insulating layer 20 is formed of at least three coil layers by forming the first coil pattern 21 and the second coil pattern 22 on the separate coil layers and forming the first and second output lead patterns 21b and 22b on the other coil layer, thus causing an increase in the vertical size of a product including it.
Especially, when increasing capacity in order to improve noise removal performance, since the second coil layer should be added simultaneously with adding the first coil layer, the vertical size of the product is more increased and the time and costs required for manufacturing processes are increased due to addition of the number of processes.